What is the difference between dissolve and limited dissolve?
As per the wiki

A dissolve


  ...effectively turns the selection into a single N-gon. Dissolve works
  slightly different based on if you have edges, faces or vertices
  selected. You can add detail where you need it, or quickly remove it
  where you don't.


While a limited dissolve


  ...reduces detail on planer faces and linear edges with an adjustable
  angle threshold.


From experience, you would use a dissolve to create one large N-gon from several vertices while a limited dissolve can be used to remove excess geometry.